There are a number of radioisotopes that are currently being utilized as markers and for other purposes in various medical, scientific, industrial and other applications. However, radioisotopes frequently have a relatively short half-life, from a few hours to a few minutes. Therefore it is generally desirable that such radioisotopes be either produced at the site where they are going to be utilized, or at a site relatively close thereto.
The short-lived radioisotopes are administered by intravenous injection or by having the subject inhale a gas containing small quantities of the radioisotope. Isotopes which are often incorporated into such gases or injection are carbon-11, nitrogen-13, oxygen, and fluorine-18. In Positron Emission Tomography (PET) facilities, these radioisotopes are derived from boron, carbon, nitrogen, and neon targets, respectively, by bombarding the targets with high-energy (approximately 6-30 MeV) protons or deuterons obtained from a particle accelerator.
The particle accelerator that is conventionally used to produce the isotope-generating particles is a cyclotron accelerator. Unfortunately, cyclotron accelerators suitable for use in the medical environment are very expensive (on the order of 1-2 million dollars), large and heavy (15-20 tons) and require a trained staff to operate and maintain the apparatus. Thus, the accelerator must be physically located in a medical center located within a short distance from the PET scanning apparatus.
Additionally, the high-energy particles produced by the cyclotron accelerator are generally used to bombard gas targets to obtain the isotopes. Gas targets must be separated from the high vacuum of the accelerator by a metallic foil window. Unfortunately, if the particles are accelerated with very high energies, the window is rapidly destroyed, thus increasing the cost of maintenance and requiring highly trained operators who must disassemble the device to replace the window.
Therefore, it is desireable to provide a method and apparatus for generating high-energy particles to induce nuclear reactions, thereby instantly producing radioisotopes. Moreover, it is desireable to provide such a method and apparatus that can be practically used for real-world medical applications and in low cost. For example, a method for generating high-energy ions would be beneficial for cancer hadron therapy because of the possible decrease in absorbed radiation.